The applicant is a child and adolescent psychiatrist with primary appointments at Children's National Medical Center (CNMC) and at The George Washington University School of Medicine (GWUSM). Dr. Thomas has extensive clinical experience in toddler psychiatry. This award will allow her to obtain the training and mentoring to become an independent clinical investigator focusing on disruptive disorders in toddlers. The educational plan includes didactic courses covering the principles and practice of clinical research, statistics, bioinfomatics, research design, and early childhood methodology. The goal of the present proposal is to examine the comorbidity between disruptive and other disorders in early childhood. The principal investigator will focus on two types of comorbidity: disruptive disorders with affective dysregulation, and disruptive disorders with neurodevelopmental difficulties (cognitive, language, motor, and neurobehavioral). The aim of this proposal is to take a first step in distinguishing these two developmental patterns of disruptive behavior with cross-sectional data. First, the PI plans to explore patterns of symptoms to verify that patients can be reliably classified into two forms of disruptive disorders: Affective/Disruptive and Neurodevelopmental/Disruptive. Second, she will test the association between these two groups of toddlers and healthy controls with characteristics of the parent and the parent-child relationship. Data from this study will inform a prospective cohort study that will examine developmental pathways to, and etiology of, early disruptive disorders, and guide strategies for intervention and prevention. These studies are important because children with early disruptive difficulties are at increased risk for continuing extemalizing difficulties, for internalizing and academic difficulties, and for adult psychopathology. This study will be conducted at the Pediatric Clinical Research Center (PCRC) at CNMC, affiliated with the Georgetown University Clinical Research Center (GCRC), and requires heavy use of the three PCRC observation rooms, and the PCRC Biostatistics/Bioinfomatics and Behavioral Phenotyping/Instrument Cores.